Return-Path: MIME-Version: 1.0 In-Reply-To: <20160720073944.GA20780@t440s> References: <20160711195044.25343-1-aar@pengutronix.de> <20160711195044.25343-21-aar@pengutronix.de> <11469f72-fa15-5545-387c-ecd051b74897@pengutronix.de> <190983bc-9467-8ff8-436c-ca1fcdfe001b@pengutronix.de> <20160719054501.GA17979@t440s.P-661HNU-F1> <20160720073944.GA20780@t440s> From: Luiz Augusto von Dentz Date: Wed, 20 Jul 2016 11:14:34 +0300 Message-ID: Subject: Re: [RFC bluetooth-next 20/20] 6lowpan: bluetooth: add new implementation To: Alexander Aring , Luiz Augusto von Dentz , linux-wpan@vger.kernel.org, kernel@pengutronix.de, kaspar@schleiser.de, Jukka Rissanen , "linux-bluetooth@vger.kernel.org" , Patrik Flykt , carlesgo@entel.upc.edu Content-Type: text/plain; charset=UTF-8 Sender: linux-wpan-owner@vger.kernel.org List-ID: Hi Johan, On Wed, Jul 20, 2016 at 10:39 AM, Johan Hedberg wrote: > Hi Alex, > > On Tue, Jul 19, 2016, Alexander Aring wrote: >> mhhh, I am not a bluetooth expert. What really means "periodically >> change is RPA" and how is this done in the Linux bluetooth? >> >> When "changing the RPA" happens, does that mean the all connections will >> be lost (unregister interface). Then the previous connections will be >> recreated (register interface) with a complete different MAC address? > > Connections aren't lost when the random address is changed. That's why > we track the hci_conn->init_addr and hci_conn->resp_addr. The way this > is dealt with e.g. the Security Manager protocol is that the connection > creation address *is* the address for the remote device throughout the > entire connection, no matter what happens to the local and remote random > address during the connection. I would expect 6LoWPAN do do something > similar. > > What was still unclear to me (maybe I missed it in the thread): does the > 6LoWPAN for LE spec require using the connection creation address or the > identity address? If it would be the latter then that's something that > will never change and the whole interface recreation issue goes away. For the MAC address I don't really know, but for the link-local IPv6 address I think the RPA shall be used: 'The IPv6 link-local address configuration described in Section 3.2.2 only reveals information about the 6LN to the 6LBR that the 6LBR already knows from the link-layer connection. This means that a device using Bluetooth privacy features reveals the same information in its IPv6 link-local addresses as in its device addresses. Respectively, a device not using privacy at the Bluetooth level will not have privacy at the IPv6 link-local address either.' -- Luiz Augusto von Dentz